1. Technical Field
The present invention relates to a technology of ejecting liquid, such as ink.
2. Related Art
A liquid ejecting head which ejects liquid, such as ink, from a plurality of nozzles is suggested in the related art. For example, in JP-A-2011-104891, a configuration in which a groove is formed on each of opposite surfaces on two substrates, and a flow path of the liquid surrounded by a wall surface of the groove is formed in the liquid ejecting head by performing laser welding with respect to the periphery of the groove and by joining the two substrates, is disclosed. In JP-A-2011-104891, considering that the welding is performed insufficiently since the heat in an end portion region of a welding part is likely to be released when laser light is radiated, and heat energy of the laser light increases in the end portion region with the thickness of the end portion region thinner than that of other parts.
In addition, for example, JP-A-2009-226943 discloses a configuration in which stagnation of the liquid in a reservoir that supplies the liquid to a compression chamber which generates pressure for ejecting the liquid is suppressed. In JP-A-2011-104891, considering that the stagnation is likely to be generated in a confluence region of the liquid supplied from a liquid supply port of a reservoir, the stagnation in the confluence region is controlled with a side wall of the reservoir protrude in the confluence region of the liquid, thereby improving bubble discharge performance in the reservoir.
However, there is a case where, in a flow path formed in a substrate by the laser welding, a flow path pipe of another flow path which communicates with the flow path is formed to protrude from a front surface of the substrate. A part which protrudes from the substrate in the flow path pipe increases to be thicker than other parts of the substrate. Therefore, when performing the welding by radiating the laser light to the substrate from the front surface on which the flow path pipe protrudes, since the protruding part of the flow path pipe is thicker than other parts of the substrate, the laser light is likely to be attenuated compared to other parts. Therefore, welding unevenness due to insufficient welding is likely to be generated. In this case, the laser light may be radiated from a flat plane side on which the flow path pipe does not protrude, but there is also a case where the laser light is not radiated from the flat plane side since a projection from the substrate increases as a structure of the flow path or a configuration of the flow path substrate has become complicated in recent years.
In the above-described JP-A-2011-104891, the flow path pipe which forms another flow path that communicates with the flow path formed on the substrate, protrudes from the substrate. However, the laser light is radiated from a side opposite to a side on which the flow path pipe protrudes on the substrate, and the fact that the laser light is radiated from the side on which the flow path pipe protrudes is not described at all, and is not even considered. Furthermore, as illustrated in JP-A-2011-104891, in a case where a part which protrudes from the substrate in the flow path pipe is pushed out of the region of the flow path in the substrate in a plan view, if the laser light is radiated from the side on which the flow path pipe protrudes, and the welding is performed, since the laser light is attenuated at a part at which the flow path pipe protrudes, welding unevenness due to insufficient welding is likely to be generated. When welding unevenness between each substrate is generated, there is a concern that air tightness of the flow path deteriorates.
In addition, since a plurality of flow paths of the liquid are provided in the liquid ejecting head, a part at which the stagnation of the liquid is generated is not limited to the confluence region of the liquid when the liquid flows into the reservoir from a supply port as described in JP-A-2009-226943. For example, there is a case where a branch flow path which branches from a main flow path of the ink is formed, and in this case, even at a branch point of the flow path, there is a concern that the stagnation of the liquid is generated. Since a part of the liquid which flows in the main flow path diverges to the branch flow path, at the branch point of the main flow path and the branch flow path, a flow of the main flow path is pulled to the branch flow path according to the flow velocity or the flow path area, and the stagnation of the liquid is likely to be generated. However, in JP-A-2009-226943, the stagnation of the liquid generated at the branch point of the flow path is not assumed. Furthermore, since the flow of the branch point between the main flow path and the branch flow path as described above is completely different from the flow of the confluence region into which the liquid flows from the supply port at a comparatively large space, such as a reservoir, as described in JP-A-2009-226943, it is not possible to employ the configuration of JP-A-2009-226943 as it is.